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#22838
New 'Binary file' detection considered harmful
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On 02/28/2016 11:13 PM, Paul Eggert wrote:
> These changes were put in partly due to security issues, not only having
> to do with grep's internals (the old 'grep' would dump core sometimes
> when given encoding errors), but also for the benefit of invokers
> expecting properly encoded text.
>
> To some extent we were stuck between a rock and a hard place here. No
> matter what 'grep' does, it will do the wrong thing for some usages. But
> overall we thought it better for grep's output to be valid text.
You are driving out demons by Beelzebub.
grep is a core component of every unix system. You cannot change the
behaviour or interface of such a fundamental tool without incurring in
substantial breakage. Keeping the old bug is far wiser than to fix it
and introduce a new bug.
Copying faulty input to the output is a preferable failure mode to
dropping part of the expected output. People do not expect grep to
validate their input but they do expect grep to produce a complete
result set.
A text file with encoding problems is a text file and not a binary file.
>> $ find /etc/ssl/certs/ | LANG= grep pem
>
> Wouldn't the following be better?
>
> find /etc/ssl/certs/ -name '*.pem'
I'm not doing that. That was just an example to show how grep now gives
incorrect results.
Many more cases can be made: any process that feeds tainted
(user-provided) strings to grep can now be made to fail. Eg. a process
that greps apache logs for known exploit signatures will now fail if the
attacker sends a bogus user-agent string.
Regards
--
Marcello Perathoner
This bug report was last modified 8 years and 256 days ago.
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